Helically-toothed-belt transmission device

Abstract

Noise and vibration of a helically-toothed-belt transmission device driven under heavy load or at a high-speed rotation, are reduced. A backlash “D” is selectively enlarged in a helically-toothed-belt transmission device that transmits drive force by meshing between a helically toothed belt and a helically toothed pulley. That is, a tooth helix angle “θ” is set in a range of −0.2≦1−W·θ/Pt≦0.75, with “Pt” being a tooth pitch, “θ” a tooth helix angle, and W the width of the belt. The backlash “D” between the helically toothed belt and the helically toothed pulley is set to be 1.6%-3% of the tooth pitch “Pt”.

1. A helically-toothed-belt transmission device for transmitting driving force by meshing between a helically-toothed belt and a helically-toothed pulley, the device being characterized in that:
 when denoting a tooth pitch as “Pt”, a tooth helix angle as “θ”, and a belt width of said helically-toothed belt as “W”, said tooth helix angle “θ” is set in a range of
   −0.2≦1 −W ·tan θ/Pt≦0.75, and;
 
 
 denoting a tooth height as “H”, a backlash between said helically-toothed belt and said helically-toothed pulley is set to be from 1.6% to 3% of said tooth pitch “Pt” when measured at half the tooth height (½ H). 
 
     
     
       2. A helically-toothed-belt transmission device for transmitting driving force by meshing between a helically-toothed belt and a helically-toothed pulley, the device being characterized in that:
 when denoting a tooth pitch as “Pt”, a tooth helix angle as “θ”, and a belt width of said helically-toothed belt as “W”, said tooth helix angle “θ” is set in a range of
   1 −W ·tan θ/Pt≦0, and;
 
 
 compressibility of said helically-toothed belt is set to be from 1.5% to 5%.